“Shin splints” is a waste-basket term to describe any pain that occurs in the leg during exercise. Shin splints is not a diagnosis as there are many causes of leg pain in the athlete, some of which require more urgent treatment than others.
Posterior tibial syndrome or “PTS” is one common cause of leg pain. The pain is located at the proximal medial cortex (upper inner edge) of the tibia or shin bone. It begins as the athlete begins to run, feels better as he warms up, and then comes back with a vengeance after exercise. It is most common in beginning runners or experienced runners who begin training too aggressively after an off-season. Changes in running surface, shoe wear or intensity of training all may contribute. An opinion is that this is most often due to periostitis or inflammation where the posterior compartment (calf) muscles attach to bone. Therefore, treatment involves anti-inflammatory medications and rest, stretching, progressive strengthening with cross-training.
Another condition that may be confused with PTS is exertional compartment syndrome. There are four groups of muscles in the legs called compartments. These compartments are enveloped in a thick fascia that can be thought of as a bag. This bag does not stretch and is important in containing the muscles as they expand with contraction. However, if the muscles swell significantly during exercise, this inability to stretch results in excessive pressure in one compartment. If this pressure becomes too high, the nerves and blood vessels begin to be compressed causing severe pain and eventually numbness and discoloration of the foot. The athlete complains of pain that gets progressively worse as they exercise and then goes away with rest. In some cases this condition requires surgery to relieve the pressure.
Stress fractures are another cause for leg pain in the athlete that should not go unrecognized. Our bones have a remarkable ability to adapt to stress. The bones bend with weight-bearing activity causing microfractures. The bone senses the location of bending or stress, and reacts by building more bone in that area. The trouble comes when an athlete increases her training intensity too rapidly. The muscles become fatigued and stop providing shock-absorption. This results in increased stress on the bone. The remodeling or building of bone cannot keep pace with the microfractures that begin to occur. If this goes on too long, a crack in the bone results. This crack causes pain with every step whether exercising or not. If the athlete continues to push through the pain, a complete fracture can occur. Treatment, depending on the severity, ranges from cross-training to casting and complete non-weightbearing.
What else can cause leg pain in the athlete? : Effort-induced DVT, popliteal artery entrapment, tennis leg, and nerve entrapment to name a few. I won’t go into detail with the rest of these, but the point I’m trying to make is that there are many causes of leg pain in the athlete and the term shin splints is an oversimplification that may lead to inappropriate treatment and prolonged inability to compete.